Performance and Limitations Flashcards
How is performance affected as air becomes less dense ?
less engine power
less thrust
less lift
What is standard atmosphere at sea level ?
15C 29.92 Hg
What are standard temp and pressure lapse rates ?
2C per 1000 ft to 36K
1 in Hg per 1000 ft to 10K
What is pressure altitude ?
Height Baseline for calibrating barometric altimeter
Measured highest and lowest pressures globally
31.00 on high end
28.00 on low end
PA of 29.92 in middle
Why is Pressure altitude important ?
basis for performance
traffic separation
assigning flight levels
Method for determining pressure altitude ?
set baro to 29.92 and read indicated altitude flight computer (using indicated and Hg)
What is density altitude ?
PA corrected for non-standard Temp
How does air density affect performance ?
density increases, better performance
density decreases, poor performance
How is density altitude determined ?
find PA, then correct for non-standard temp variations
What does density altitude mean to aircraft performance ?
The aircraft will perform as if it was at that altitude.
normally aspirated engines
What factors affect density altitude ?
changes in
altitude
temperature
humidity
What effect does atmospheric pressure have on air density ?
its proportional
higher pressure causes higher density altitude
What effect does temperature have on air density ?
varies inversely
warmer causes density decrease
colder causes density increase
What effect does humidity have on air density ?
as water vapor increase, density decreases
What is relative humidity ?
percentage of maximum amount of water vapor the air can hold
What effect does landing at high-elevation airports have on ground speed ?
true airspeed is faster, resulting in faster ground speed.
greater distance to clear obstacles
longer ground roll etc
What are some of the elements of aircraft performance ?
Takeoff distance landing distance rate-of-climb ceiling payload Range Speed Maneuverability Stability Fuel economy
What is relationship to lift, weight thrust in steady state flight ?
lift = weight thrust = drag
What are the types of drag ?
induced (wing drag)
parasitic (aircraft skin)
What is induced drag ?
drag as a by-product of lift
What is parasitic drag ?
friction of air moving over the aircraft
How does drag increase as speed increases ?
2x speed = 4x drag
Define the term “service ceiling”
Max altitude of aircraft where
Vy = 100 FPM
Max weight
Will aircraft always be able to climb at service ceiling ?
No, depends on density altitude
What is the definition of absolute ceiling ?
altitude at which a climb is not longer possible
What is power loading ?
Dividing total weight of airplane by brake HP
What is wing loading ?
Dividing total weight of airplane by wing area
What is maximum range ?
max distance for given fuel.
obtain by L/D max
What is maximum endurance ?
max TIME for given fuel
obtained at min power for flight
What is ground effect ?
interference of ground with airflow
reduction of upwash and downwash
occurs within wingspan of ground
What problems can occur by ground effect ?
Landing - less drag causes float
Takeoff - excess weight airborne in ground effect but marginal or no climb out of ground effect
What does “flight in region of normal command” mean ?
while level
higher airspeed requires higher power
lower airspeed requires lower power
What does “flight in region of reverse command” mean ?
“behind the power curve”
airspeed between min pwr and stall speed
a decrease in speed must be accompanied by and increase in power
What are examples of operating “behind the power curve” ?
high pitch
powered approach for short-field landing
soft-field take-off and climb
How does runway and gradient affect performance ?
alt to hard and smooth increase ground roll
increase gradient increases ground roll
What factors affect take-off and landing ?
Air density surface wind runway surface runway gradient weight powerplant thrust
How do you plan for rejected takeoff ?
50/70 rule if not 70% Airspeed (54kts) by 50% runway, abort power idle max braking directional control
What does 75% BHP mean ?
Brake horsepower
power at prop shaft
delivering 75% of engine HP to prop shaft
at sea level
How would you lean an engine ?
Tach Method: mixture for peak RPM then lean to rough
Fuel flow: published amount
EGT: Lea until EGT peak then come down (50 degrees)
What is normal climb out speed.
120KIAS (130)
What is Vr ?
77 - 80 KIAS
What is airspeed at obstacle ?
85 KIAS
What is airspeed for Flaps retract ?
90 KIAS
What is Vy ?
best rate of climb. 103 KIAS (102 @ 10K)
What is Vx ?
best climb angle. 88 KIAS
How do you set cruise power in SR22T ?
30.5 MP.
Lean to Cyan marker
Engine assist for 50 - 75 degrees below peak EGT
What is stall speed in clean configuration ?
74 KIAS @3600 lb, 0 bank, FWD CG
72 KIAS @3600 lb, 0 bank, AFT CG
Flaps 50% speed ?
150
Flaps 1005 speed ?
110
Vpd ?
Parachute Deployment speed 140 KIAS
Vo ?
Operating Maneuvering Speed. 140 KIAS
Vne ?
Never Exceed Speed
205 KIAS To 17.5K
175 KIAS 17.5K to 25K
Vno ?
Max Structural Cruising Speed
176 KIAS To 17.5K
150 KIAS to 25K
What is stall speed with 50% flaps ?
70 KIAS at 3600 lb, 0 bank, FWD CG
69 KIAS at 3600 lb, 0 bank, AFT CG
What is stall speed with 100% flaps ?
64 KIAS at 3600 lb, 0 bank, FWD CG
63 KIAS at 3600 lb, 0 bank, AFT CG
What performance characteristics will be adversely affected when an aircraft is overloaded ?
Higher takeoff speed Longer takeoff run Reduced rate and angle of climb Lower maximum altitude Shorter range Reduced cruising speed Reduced Maneuverability Higher stalling speed Higher approach and landing speed Longer landing roll Excessive weight on nose wheel
What responsibilities does the owner/operator have if weight and balance has changed on an aircraft ?
Changes documented in
POH
FAA form 337
What is CG ?
Center of Gravity
Point at which aircraft would balance in space
What effect of FWD CG ?
Higher stall speed due to increased wing loading
Slower cruise speed due to increased drag, higher AOA
More stable
Greater back pressure required
What effect of AFT CG ?
Lower stall speed
Higher cruise speed
Less stable - stall and spin recovery more difficult